Vehicle engines, in particular petrol fuel-powered combustion engines but also other engines known in the art, are typically coupled to a fuel system including the fuel tank and other components configured to provide fuel to the engine or the engine system. A majority of these systems also include a so called evaporation fuel purge (EVAP) system for preventing fuel vapours in the fuel tank from escaping into the atmosphere. In this context, it should be noted that a fuel system is typically not allowed to leak more fuel evaporative in the atmosphere than legislation permits. In general, the EVAP system is configured to trap fuel vapours from the fuel tank and temporarily stores them in a charcoal canister. When the vehicle engine is running under certain conditions, the fuel vapours are purged from the canister and burned inside the engine. The canister needs to be drained of hydro carbons to make sure that emissions are still kept to satisfied level. In order to determine when the canister should be emptied, the EVAP system may also include a purge valve or any other control mechanism adapted to control the amount of fuel vapour intended to be purged from the charcoal canister. In many vehicles such as modern cars, the purge valve is controlled by the engine computer. When the engine is off, the purge valve is closed. When the engine is running and fully warmed up, the engine computer gradually opens the purge valve to permit some amount of fuel vapour to be transferred from the charcoal canister to be burned in the engine.
In addition, some system may also include a purge ejector to further improve the process of emptying the canister in an effective manner. A purge ejector can be designed in several different manners. By way of example, the purge ejector typically includes a nozzle to raise the flow velocity of the air flowing through the fluid passages between the canister and the engine system and one or several check valves to control the flow of fuel vapour between the components making up the EVAP system and the engine system.
However, current regulatory conditions in the automotive market have led to an increasing demand to improve the process of purging fuel vapour from the canister to the engine in present vehicles. Further, with increased attention to environmental problems, fuel vapour regulations are becoming more and more stringent. These regulatory conditions must be balanced with the demands on the engine system for high performance for a vehicle. These problems and demands are particularly apparent for engine system using a compressor such as a turbo charger.
In addition, there are several different solutions to arrange the purge ejector in the fluid passage between the canister and the engine system, which partly depends on the design of the engine system and the EVAP system.
It would be beneficial if it could be ensured that the purge ejector or the purge ejector assembly for an engine can be installed in a known or commercially-available vehicle without substantial changes to the fuel system or the EVAP system, while enabling an effective purge of the canister during operation of the engine system.